1. Field of the Invention
The present invention relates to a process for producing a controlled drug-release contact lens and a controlled drug-release contact lens thereby produced. More particularly, it relates to a process for producing a controlled drug-release contact lens which has high mechanical strength and excellent durability and which is excellent in safety to eye tissues while the gradual releasing property lasts for a long period of time, and a controlled drug-release contact lens produced by such a process.
2. Description of the Background
Heretofore, a cornea disease curing device having a predetermined amount of a drug incorporated in a gradually soluble contact lens-shaped material (JP-Y-57-27456 or a contact lens employing a sustained-release agent capable of slowly dispersing a drug in an eye (JP-A-62-10328 and JP-A-62-10329) has been proposed as a controlled drug-release contact lens. However, such a cornea disease curing device or a contact lens has a drawback the property for gradually releasing the drug hardly lasts, and the curing effects can not adequately be obtained.
Under the circumstances, for the purpose of maintaining the property for gradually releasing the drug for a long period of time, a contact lens has been proposed which has a chamber in its interior, so that a drug to soften the cornea is contained in the chamber, and the drug is gradually supplied to the eye during use of the contact lens (JP-A-7-500267). However, such a contact lens is one produced by bonding front and rear faces of the lens by an adhesive and, as such, has a drawback that the mechanical strength is inadequate, it is poor in durability, and safety to eye tissues is questionable due to the adhesive employed.